Optical-based technologies are increasingly utilized in data transmission as Internet and other data networks carry greater amounts of data. Among the elements utilized in such technologies are optical modulators, which are electronic devices that modulate beams of light.
In particular, a device such as a metal-oxide-semiconductor (MOS) capacitor structure embedded in a silicon waveguide may be utilized to produce high-speed optical phase modulation. A silicon optical modulator is based on modulation of the refractive index of silicon.
In conventional optical modulators, polycrystalline silicon (commonly referred to as polysilicon, poly-Si, or poly) is used in fabrication of a device, the polysilicon providing the light carrying waveguide medium that is modulated in the device. Polysilicon is composed of multiple silicon crystals, and may be deposited on a semiconductor wafer through certain processes such as pyrolyzing silane at certain required temperatures.
However, the use of polysilicon in an optical modulator results in high optical loss through the polysilicon waveguide. The optical losses thereby limit the usefulness of the material for optical modulation devices, particularly for devices intended to operate at high speeds where the optical losses become greater. Further, the use of polysilicon can cause difficulties in fabrication of devices for high speed communications and interconnect applications, including difficulties in bonding of other components in an apparatus.